1. Field of the Invention
The present invention generally relates to a method of motion detection, and more particularly, to a method for motion detection of a horizontal line.
2. Description of Related Art
With development of multimedia technique, requirement for image quality is substantially increased. The image quality may be influenced by the noises generated during image capturing, signal conversion and signal transmission. Therefore, an image processing technique is required to eliminate the noises that may be sensed by human eyes. The image processing methods for noise reduction commonly include a spatial noise-reduction process and a temporal noise-reduction process.
The spatial noise-reduction process applies a filter to perform spatial filtering process on the pixels of a current field, so as to smooth and soften the field, and reduce a visual perception of the human eyes for the noises. However, such method generally leads to image blurs, which may influence the presentation of image details, such as edges and textures, for example.
The temporal noise-reduction process references information of a previous field, so as to perform temporal filtering process to the pixels of the current field. Since the current field is highly related to the previous field, the temporal noise-reduction process can maintain and reserve details of the field. However, when the temporal filtering process is performed on a moving object within the field, motion blurs may occur on the edges of the moving object. Therefore, a motion detection algorithm is provided to detect the moving pixels in the field, so as to adjust an intensity of the temporal filtering for eliminating the motion blurs.
Generally speaking, motion detection uses differences between corresponding pixels in the same parity field to determine whether the designated pixels are moving pixels or not. If the difference is larger than a preset threshold, it means a variation is occurred in the content of the video and the corresponding pixels are determined as the moving pixels, and if the difference is smaller than the preset threshold, it means no variation is occurred in the content of the video and the corresponding pixels are determined as the static pixels.
Through the motion detection as described above, motion information of pixels of the moving object is obtained and referenced for determining whether to use a spatial interpolation or a temporal interpolation method to generate the required field data, in which the temporal interpolation is used for calculating values of pixels in an area with no moving object and the spatial interpolation is used for calculating values of pixels in an area with the moving object.
As described in the above, the motion detection algorithm is complicated, especially for the motion detection of horizontal lines. The motion of the horizontal lines can be classified into the horizontal lines moving vertically and the horizontal lines moving horizontally. For the horizontal lines moving vertically, a spatial interpolation is required to generate field data thereof. For the horizontal lines moving horizontally, they are also detected as a moving area and the spatial interpolation is used to generate field data thereof. However, a variation between the field data of adjacent two fields that are respectively generated through the spatial interpolation usually results in appearance of flickers, which will influence quality of vision substantially.